1. Electrical Safety

2. Terminal Learning Objective
Upon completion of this module, participants will understand the hazards of electricity and the need for proper planning and control methods to eliminate or reduce those hazards.

3. Enabling Learning Objectives
In this module, we will:
Discuss the hazards of electricity
Describe ways to control those hazards
Identify several safety-related work practices
Explain how hazards can be prevented with thorough planning and training

4. Electricity - The Dangers
About 5 workers are electrocuted every week
Causes 12% of young worker workplace deaths
Takes very little electricity to cause harm
Significant risk of causing fires

5. Electricity – How it Works
Electricity is the flow of energy from one place to another
Requires a source of power: usually a generating station
A flow of electrons (current) travels through a conductor
Travels in a closed circuit

6. Electrical Terms Current – electrical movement (measured in amps)
Circuit – complete path of the current. Includes electricity source, a conductor, and the output device or load (such as a lamp, tool, or heater)
Resistance – restriction to electrical flow
Conductors – substances, like metals, with little resistance to electricity that allow electricity to flow
Grounding – a conductive connection to the earth which acts as a protective measure
Insulators – substances with high resistance to electricity like glass, porcelain, plastic, and dry wood that prevent electricity from getting to unwanted areas

7. Electrical Injuries There are four main types of electrical injuries:
Direct
Electrocution or death due to electrical shock
Electrical shock
Burns
Indirect
Falls

8. Electrical Shock There are four main types of electrical injuries:
An electrical shock is received when electrical current passes through the body.
You will get an electrical shock if a part of your body completes an electrical circuit by…
Touching a live wire and an electrical ground, or
Touching a live wire and another wire at a different voltage.

9. ** LOW VOLTAGE DOES NOT MEAN LOW HAZARD
Shock Severity
Severity of the shock depends on:
Path of current through the body
Amount of current flowing through the body (amps)
Duration of the shocking current through the body
** LOW VOLTAGE DOES NOT MEAN LOW HAZARD

10. Dangers of Electrical Shock
Severity of the shock depends on:
Currents above 10 mA* can paralyze or “freeze” muscles.
Currents more than 75 mA can cause a rapid, ineffective heartbeat – death will occur in a few minutes unless a defibrillator is used.
75 mA is not much current – a small power drill uses 30 times as much.
*1/10 of an ampere (amp)
Defibrillator in use

11. Burns Most common shock-related injury
Occurs when you touch electrical wiring or equipment that is improperly used or maintained
Typically occurs on hands
Very serious injury that needs immediate attention

12. Falls Electric shock can also cause indirect injuries
Workers in elevated locations who experience a shock may fall, resulting in serious injury or death

13. Electrical Hazards and How to Control Them
Electrical accidents are caused by a combination of three factors:
Unsafe equipment and/or installation,
Workplaces made unsafe by the environment, and
Unsafe work practices.

14. Cover removed from wiring or breaker box
Hazard – Exposed Electrical Parts
Cover removed from wiring or breaker box

15. Control – Isolate Electrical Parts
Use guards or barriers
Replace covers
Guard live parts of electric equipment operating at 50 volts or more against accidental contact

16. Control – Isolate Electrical Parts, Cabinets, Boxes & Fittings
Conductors going into them should be protected, and unused openings should be closed.

17. Photo shows violations of these two requirements
Control – Close Openings
Junction boxes, pull boxes and fittings should have approved covers
Unused openings in cabinets, boxes and fittings should be closed (no missing knockouts)
Photo shows violations
of these two requirements

18. Hazard – Overhead Power Lines
Usually not insulated
Examples of equipment that can contact power lines:
Crane
Ladder
Scaffold
Backhoe
Scissors lift
Raised dump truck bed
Aluminum paint roller

19. Control - Overhead Power Lines
Stay at least 10 feet away
Post warning signs
Assume that lines are energized
Use wood or fiberglass ladders, not metal
Power line workers need special training & PPE

20. Hazard - Inadequate Wiring
Hazard - wire too small for the current
Example - portable tool with an extension cord that has a wire too small for the tool
The tool will draw more current than the cord can handle, causing overheating and a possible fire without tripping the circuit breaker
The circuit breaker could be the right size for the circuit but not for the smaller-wire extension cord
Wire Gauge
WIRE
Wire gauge measures wires ranging in size from number 36 to 0 American wire gauge (AWG)

21. Must be 3-wire type and designed for hard or extra-hard use
Control – Use the Correct Wire
Wire used depends on operation, building materials, electrical load, and environmental factors
Use fixed cords rather than flexible cords
Use the correct extension cord
Must be 3-wire type and designed for hard or extra-hard use

22. Hazard – Defective Cords & Wires
Plastic or rubber covering is missing
Damaged extension cords & tools

23. Hazard – Damaged Cords Cords can be damaged by: Aging
Door or window edges
Staples or fastenings
Abrasion from adjacent materials
Activity in the area
Improper use can cause shocks, burns or fire

24. Control – Cords & Wires Insulate live wires Check before use
Use only cords that are 3-wire type
Use only cords marked for hard or extra-hard usage
Use only cords, connection devices, and fittings equipped with strain relief
Remove cords by pulling on the plugs, not the cords
Cords not marked for hard or extra-hard use, or which have been modified, should be taken out of service immediately

25. Permissible Use of Flexible Cords
DO NOT use flexible wiring where frequent inspection would be difficult or where damage would be likely.
Flexible cords should not be...
Run through holes in walls, ceilings, or floors;
Run through doorways, windows, or similar openings (unless physically protected);
Hidden in walls, ceilings, floors, conduit or other raceways

26. Grounding
Grounding creates a low-resistance path from a tool to the earth to disperse unwanted current.
When a short or lightning occurs, energy flows to the ground, protecting you from electrical shock, injury and death.

27. Hazard – Improper Grounding
Tools plugged into improperly grounded circuits may become energized
Broken wire or plug on extension cord
Some of the most frequently violated OSHA standards

28. Control – Ground Tools & Equipment
Ground power supply systems, electrical circuits, and electrical equipment
Frequently inspect electrical systems to insure path to ground is continuous
Inspect electrical equipment before use
Don’t remove ground prongs from tools or extension cords
Ground exposed metal parts of equipment

29. (ground-fault circuit interrupter)
Control – Use GFCI
(ground-fault circuit interrupter)
Protects you from shock
Detects difference in current between the black and white wires
If ground fault detected, GFCI shuts off electricity in 1/40th of a second
Use GFCI’s on all 120-volt, single-phase, 15- and 20-ampere receptacles, or have an assured equipment grounding conductor program

30. Control – Assured Equipment Grounding Conductor Program
Program should cover:
All cord sets
Receptacles not part of a building or structure
Equipment connected by plug and cord
Program requirements include:
Specific procedures adopted by the employer
Competent person to implement the program
Visual inspection for damage of equipment connected by cord and plug

31. Hazard – Overloaded Circuits
Hazards may result from:
Too many devices plugged into a circuit, causing heated wires and possibly a fire
Damaged tools overheating
Lack of over-current protection
Wire insulation melting, which may cause arcing and a fire in the area where the overload exists, even inside a wall

32. Control – Electrical Protective Devices
Automatically opens circuit if excess current from overload or ground-fault is detected – shutting off electricity
Includes GFCI’s, fuses, and circuit breakers
Fuses and circuit breakers are over- current devices. When too much current:
Fuses melt
Circuit breakers trip open

33. Power Tool Requirements
Have a three-wire cord with ground plugged into a grounded receptacle, or
Be double insulated, or
Be powered by a low-voltage isolation transformer

34. Tool Safety Tips Use gloves and appropriate footwear
Keep cords away from heat, oil, & sharp edges
Disconnect when not in use and when changing
Store in dry place when not using
Don’t use in wet/damp conditions
Keep working areas well lit
Ensure not a tripping hazard
Don’t carry a tool by the cord
Don’t yank the cord to disconnect it
Accessories such as blades & bits
Remove damaged tools from use

35. Preventing Electrical Hazards – Tools
Inspect tools before use
Use the right tool correctly
Protect your tools
Use double insulated tools

36. Temporary Lights
Protect from contact and damage, and don’t suspend by cords unless designed to do so.

37. Clues that Electrical Hazards Exist
Tripped circuit breakers or blown fuses
Warm tools, wires, cords, connections, or junction boxes
GFCI that shuts off a circuit
Worn or frayed insulation around wire or connection

38. Lockout and Tagging of Circuits
Apply locks to power source after de-energizing
Tag deactivated controls
Tag de-energized equipment and circuits at all points where they can be energized
Tags should identify equipment or circuits being worked on

39. Safety-Related Work Practices
To protect workers from electrical shock:
Use barriers and guards to prevent passage through areas of exposed energized equipment
Pre-plan work, post hazard warnings and use protective measures
Keep working spaces and walkways clear of cords

40. Safety-Related Work Practices
Use special insulated tools when working on fuses with energized terminals
Don’t use worn or frayed cords and cables
Don’t fasten extension cords with staples, hang from nails, or suspend by wire

41. Preventing Electrical Hazards – Planning
Plan your work with others
Plan to avoid falls
Plan to lock-out and tag-out equipment
Remove jewelry
Avoid wet conditions and overhead power lines

42. Avoid Wet Conditions
If you touch a live wire or other electrical component while standing in even a small puddle of water you’ll get a shock.
Damaged insulation, equipment, or tools can expose you to live electrical parts.
Improperly grounded metal switch plates & ceiling lights are especially hazardous in wet conditions.
Wet clothing, high humidity, and perspiration increase your chances of being electrocuted.

43. Preventing Electrical Hazards – PPE
Proper foot protection (not tennis shoes)
Rubber insulating gloves, hoods, sleeves, matting, and blankets
Hard hat (insulated– nonconductive)

44. Preventing Electrical Hazards – Proper Wiring and Connectors
Use and test GFCI’s
Check switches and insulation
Use three prong plugs
Use extension cords only when necessary & assure in proper condition and right type for job
Use correct connectors

45. Training
Train employees working with electric equipment in safe work practices, including:
De-energize electric equipment before inspecting or repairing
Using cords, cables, and electric tools that are in good repair
Lockout/Tagout recognition and procedures
Use appropriate protective equipment

46. Review In this module, we: Discussed the hazards of electricity
Described ways to control those hazards
Identified several safety-related work practices
Explained how hazards can be prevented with thorough planning and training

47. Questions?